Gates is apparently the consummate bureaucrat, unencumbered by any particular personal or political standards, and thus able to serve in any administration. I've heard him referred to as a bureaucrat often since he decided to stay on with Obama.
But it's still bizarre that he saw any reason at all to make those remarks at this time, before that audience.
As a clever bureaucrat, he is taking the proverbial wind out of Obama’s sails for his tremendous act of executive courage and decisiveness (at least in the MSM narrative).